Current blow-molding machinery is designed to manufacture hollow plastic containers by extruding a parison between opposed, parted mold halves. The mold is then closed and air is injected into the parison, blowing and distending it outward so that it conforms itself to the inner contours of the mold which match the outer shape of the bottle to be produced. The newly-formed container is allowed to harden, then is extracted or dropped from the mold.
Some plastic bottle manufacturers produce blow-molded articles by using rotary blow-molding machines. A typical rotary blow-molding machine includes a rotating carrousel that carries two or more mold stations around a circular mold station path. Each mold station includes a mold with a mold cavity. The carrousel is indexed to hold each mold station momentarily motionless at each of a series of blow molding "work stations". A "work station" is a position where each mold station must pause in its circular path for a particular operation to be carried out. A "work station series" is a progression of work stations necessary to complete a blow molding process on a single mold station in a single carrousel revolution. Blow molding operations are carried out sequentially on each mold as each mold station rotates through a work station series, pausing momentarily at each work station in the series.
Rotary blow-molding machines may, of course, include any number of mold and work stations, and may include more than one work station series arranged around a single mold station path.
The final work station in a work station series is the article take-out mechanism where the blown articles are released or extracted from their respective molds. These article take-out mechanisms can operate to remove articles while the mold is paused at the work station or during continuous rotation of the mold past the work station.
An example of the latter of those two types of take-out mechanisms is shown in U.S. Pat. No. 4,902,217 to Martin et al. which discloses a rotary take-out mechanism with an oscillating turret arm mounted adjacent a rotary mold carrousel at an article take-out work station. One end of the turret arm is pivotally mounted to a carrousel axle. The other end of the turret arm, i.e., the "outer" end, extends radially outward from the carrousel axis beyond the carrousel outer diameter. A take-out member is mounted on the turret arm outer end. As the molds revolve around the carrousel axle, the turret arm repeatedly swings the take-out member upward and downward through a small arcuate path just outside the circular path of the molds as the molds pass the take-out work station. The downward swing of the turret arm matches the movement of the orbiting molds thus canceling relative motion between the molds and the take-out member over a small arcuate distance. This temporary lack of relative motion provides enough time for the take-out member to engage and extract blown articles from the molds as they pass through the take-out work station.
The take-out member of the Martin et al. patent comprises four article-engagement members mounted at spaced locations around the circumference of a wheel. The wheel is rotatably mounted at the turret arm outer end on an axis parallel to that of the carrousel axis. The wheel is synchronized to rotate in an angular direction opposite that of the carrousel. As each article-engagement member rotates past a carrousel mold it engages a blown article, removes it from its mold, rotates it downward and away from the carrousel, and places it in an upright position on an article-conveyor mechanism.
Take-out mechanisms of the type disclosed in the Martin et al. patent are inherently complex as they must synchronize with and track the continuous arcuate motion of the molds as the molds pass an article take-out work station. What is needed is a simplified article take-out mechanism designed to remove blown articles from an indexing-type blow-molding apparatus that momentarily holds each mold stationary at an article take-out work station.